A seat reclining apparatus for a vehicle which is stable and stationary when the vehicle vibrates, or oscillates is required in recent years.
A known seat reclining apparatus for a vehicle disclosed in JP2012-046091A (hereinafter, referred to as Patent reference 1) includes an inner gear plate and an outer gear plate which are mounted to the seat reclining apparatus for the vehicle in a relatively rotatable manner while shifting, or changing a meshing position of the inner gear plate and outer gear plate with one another. Because the number of the inner teeth of the inner gear plate is different from the number of the outer teeth of the outer gear plate, a clearance is provided between the inner gear plate and the outer gear plate in a manner that the inner gear plate and the outer gear plate are eccentrically positioned. A pair of wedge members is positioned within the clearance to be in contact with and supported by an inner circumferential surface of a hole portion of the outer gear plate and an outer circumferential surface of a center cylindrical portion of the inner gear plate. A ring spring which locks a relative rotation of the inner gear plate and the outer gear plate by biasing the pair of the wedge members in a direction in which the clearance is narrower so that the pair of the wedge members is in contact with the inner circumferential surface of the hole portion of the outer gear plate while being in contact with the outer circumferential surface of the center cylindrical portion of the inner gear plate at each respective point.
An operating portion is positioned within the clearance and presses and rotates the outer gear plate relative to the inner gear plate by pressingly moving one of the pair of the wedge members in a direction in which the clearance is wider by the rotation of the operating portion. Further, a brake spring is included to prevent the pair of the wedge members from being loosened.
According to the seat reclining apparatus for the vehicle disclosed in Patent reference 1, the pair of the wedge members is in contact with and supported by only two portions which are the inner circumferential surface of the hole portion of the outer gear plate and the outer circumferential surface of the center cylindrical portion of the inner gear plate. Accordingly, in a case where the vehicle vibrates, or oscillates, the pair of the wedge members which locks the relative rotation of the outer gear and the inner gear may be loosened easily and the wedging action does not take place effectively because the pair of the wedge members moves easily.
A need thus exists for a seat reclining apparatus for a vehicle which is not susceptible to the drawback mentioned above.